These Valley counties have declared an emergency to fight virus that could ruin tomato crops

The San Joaquin County Board of Supervisors declared a local emergency on Tuesday due to a virus that threatens to decimate tomato crops.

A small insect known as the beet leafhopper spreads the beet curly top virus, which causes plants to turn yellow and stop growing.

Pest control advisers who walked through tomato fields in San Joaquin County found tomatoes that had been infected with the virus on Fabian Tract, Roberts Island, and Union Island, prompting the county's director of emergency services to proclaim an emergency last Wednesday.

The board of supervisors ratified the proclamation, a decision which will enable farmers to use neonicotinoid pesticides to combat beet curly top virus during the growing season.

Why declare a local emergency?

New regulations in California that went into effect on Jan. 1 restrict the use of neonicotinoid pesticides on various fruits and vegetables, including tomatoes, in order to protect honeybees and other pollinators.

However, there is an exception which allows neonicotinoid pesticides to be used when counties declare local emergencies.

"There are no alternative materials that are highly efficacious towards (beet curly top virus). Without neonicotinoids, growers would be required to apply alternative active ingredients that are not systemic and will provide temporary relief only if applied multiple times at the early stages of the crop’s growth, greatly increasing the treatment cost on affected acres," Agricultural Commissioner Kamaljit Bagri wrote in a letter to the board.

"The efficacy of this alternative treatment will fade throughout the growing season and no other efficacious means of control post early stages of the crop’s growth are available to the tomato growers at this time," Bagri said.

What is a beet leafhopper?

The small insects, which are about 3 millimeters long, can accumulate the beet curly top virus while feeding on annual and perennial weeds.

Once the beet leafhoppers accumulate the virus, they spread it as they feed on agricultural commodities in search of new host plants, potentially causing severe damage and crop losses.

Beet leafhoppers can infect 300 plant species, including crops and weeds, according to the California Department of Food and Agriculture.

What's at stake?

While the virus is known to affect peppers, squash, and pumpkins, it has caused "significant economic damage to tomatoes," according to county officials.

San Joaquin County has a total of 21,673 acres used for tomato production at an annual cost of $5,248 per acre, resulting in a harvest valued at approximately $114 million in 2023.

The beet curly top virus is not new to the region. The virus has been a known cause of serious crop damage in the San Joaquin Valley since the early 1900s.

The California Department of Food and Agriculture established a program in 1943 to manage its economic impact.

This year, a reported increase in populations of the beet leafhopper raised concerns about the beet curly top virus in the Central Valley.

Local emergencies have also been declared in Fresno, Kern, Madera, Merced, and Stanislaus counties.

In 60 days, the San Joaquin County Board of Supervisors will determine if they need to continue the local emergency or terminate it.

Record reporter Hannah Workman covers news in Stockton and San Joaquin County. She can be reached at hworkman@recordnet.com or on Twitter @byhannahworkman. Support local news, subscribe to The Stockton Record at https://www.recordnet.com/subscribenow.